Lucio Gordan, MD, Florida Cancer Specialists, discusses results from a study analyzing the impact of late dosing on testosterone suppression for patients with prostate cancer. The study looked at two extended-release forms of leuprolide acetate, the most commonly used luteinizing hormone-releasing hormone agonist in the United States: in situ gel technology and microsphere technology.

These results were presented at the virtual 2021 National Comprehensive Cancer Network (NCCN) Annual Conference.

Lucio Gordan:  My name is Lucio Gordan. I'm the Managing Physician and President of Florida Cancer Specialists. I have the pleasure of presenting new findings that when dosing is late, the ability of two different leuprolide products in maintaining testosterone suppression may be distinct, therefore, indicating that not all products are equal.

The reason this is important is that ADT for treatment of advanced prostate cancer relies on testosterone suppression to castration level for less than 50. There's significant evidence that when we maintain low testosterone levels that correlates well with approved clinical outcomes -- progression-free survival, overall survival, and response rates.

However, when dosing is late and unfortunately can be often late in the real world -- and this is a real-world study -- it may cause testosterone level to rise above castration levels, which may lead to disease progression.

As ADT therapies are not necessarily interchangeable due to different delivery systems, this study evaluated the impact of late dosing on testosterone suppression for two LHRH therapies. One was the Gel-LA, and Msphere-LA that deliver leuprolide through different technologies.

In our study on figure two, you can see that injection timeline was similar between the two therapies in 27%. Nearly 30% of injections were actually late for both drugs, and that's a problem that needs to be rectified. I'll comment on this in our conclusions here.

The figure three of our study showed that when injections were late, 25% of Msphere-LA injections have testosterone levels higher than 50 ng/dl or above castration levels compared to 18% for the Gel-LA. This is about 1.5 times difference between the two therapies or delivery systems.

Additionally, when looking at six-month formulation, the Msphere had twice more T levels above 50 compared to the Gel-LA, so it is of concern.

Overall, late dosing is relatively common at almost 30% in the real world which may have serious clinical implications when testosterone level is not at castration levels. The study's results show that Gel-LA is more effective than Msphere at maintaining testosterone suppression.

Clinicians should modify practices to increase dosing schedule adherence, monitor testosterone levels routinely and frequently, and consider prescribing therapies that are able to maintain testosterone suppression below castration levels.

I thank you very much for your attention. Thank you, Journal of Clinical Pathways.

Gordan LN, Atkinson SN, Bold-Houle DM, et al. Impact of Late Dosing on Testosterone Suppression With Two Different Leuprolide Acetate Formulations: In Situ Gel and Microsphere – an Analysis of US Clinical Data. Presented at: the NCCN 2021 Virtual Annual Conference; March 18-20, 2021. Abstract CLO21-014.

Dr Gordan reports no relevant financial relationships.